From: Igor Stoppa <igor.stoppa@gmail.com>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>,
Kees Cook <keescook@chromium.org>,
Matthew Wilcox <willy@infradead.org>,
Dave Chinner <david@fromorbit.com>,
James Morris <jmorris@namei.org>,
Michal Hocko <mhocko@kernel.org>,
kernel-hardening@lists.openwall.com,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Cc: igor.stoppa@huawei.com, Dave Hansen <dave.hansen@linux.intel.com>,
Jonathan Corbet <corbet@lwn.net>,
Laura Abbott <labbott@redhat.com>,
Chris von Recklinghausen <crecklin@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH 09/17] prmem: hardened usercopy
Date: Wed, 24 Oct 2018 00:34:56 +0300 [thread overview]
Message-ID: <20181023213504.28905-10-igor.stoppa@huawei.com> (raw)
In-Reply-To: <20181023213504.28905-1-igor.stoppa@huawei.com>
Prevent leaks of protected memory to userspace.
The protection from overwrited from userspace is already available, once
the memory is write protected.
Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com>
CC: Kees Cook <keescook@chromium.org>
CC: Chris von Recklinghausen <crecklin@redhat.com>
CC: linux-mm@kvack.org
CC: linux-kernel@vger.kernel.org
---
include/linux/prmem.h | 24 ++++++++++++++++++++++++
mm/usercopy.c | 5 +++++
2 files changed, 29 insertions(+)
diff --git a/include/linux/prmem.h b/include/linux/prmem.h
index cf713fc1c8bb..919d853ddc15 100644
--- a/include/linux/prmem.h
+++ b/include/linux/prmem.h
@@ -273,6 +273,30 @@ struct pmalloc_pool {
uint8_t mode;
};
+void __noreturn usercopy_abort(const char *name, const char *detail,
+ bool to_user, unsigned long offset,
+ unsigned long len);
+
+/**
+ * check_pmalloc_object() - helper for hardened usercopy
+ * @ptr: the beginning of the memory to check
+ * @n: the size of the memory to check
+ * @to_user: copy to userspace or from userspace
+ *
+ * If the check is ok, it will fall-through, otherwise it will abort.
+ * The function is inlined, to minimize the performance impact of the
+ * extra check that can end up on a hot path.
+ * Non-exhaustive micro benchmarking with QEMU x86_64 shows a reduction of
+ * the time spent in this fragment by 60%, when inlined.
+ */
+static inline
+void check_pmalloc_object(const void *ptr, unsigned long n, bool to_user)
+{
+ if (unlikely(__is_wr_after_init(ptr, n) || __is_wr_pool(ptr, n)))
+ usercopy_abort("pmalloc", "accessing pmalloc obj", to_user,
+ (const unsigned long)ptr, n);
+}
+
/*
* The write rare functionality is fully implemented as __always_inline,
* to prevent having an internal function call that is capable of modifying
diff --git a/mm/usercopy.c b/mm/usercopy.c
index 852eb4e53f06..a080dd37b684 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -22,8 +22,10 @@
#include <linux/thread_info.h>
#include <linux/atomic.h>
#include <linux/jump_label.h>
+#include <linux/prmem.h>
#include <asm/sections.h>
+
/*
* Checks if a given pointer and length is contained by the current
* stack frame (if possible).
@@ -284,6 +286,9 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user)
/* Check for object in kernel to avoid text exposure. */
check_kernel_text_object((const unsigned long)ptr, n, to_user);
+
+ /* Check if object is from a pmalloc chunk. */
+ check_pmalloc_object(ptr, n, to_user);
}
EXPORT_SYMBOL(__check_object_size);
--
2.17.1
next prev parent reply other threads:[~2018-10-23 21:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20181023213504.28905-1-igor.stoppa@huawei.com>
2018-10-23 21:34 ` [PATCH 02/17] prmem: write rare for static allocation Igor Stoppa
2018-10-25 0:24 ` Dave Hansen
2018-10-29 18:03 ` Igor Stoppa
2018-10-26 9:41 ` Peter Zijlstra
2018-10-29 20:01 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 03/17] prmem: vmalloc support for dynamic allocation Igor Stoppa
2018-10-25 0:26 ` Dave Hansen
2018-10-29 18:07 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 04/17] prmem: " Igor Stoppa
2018-10-23 21:34 ` [PATCH 05/17] prmem: shorthands for write rare on common types Igor Stoppa
2018-10-25 0:28 ` Dave Hansen
2018-10-29 18:12 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 06/17] prmem: test cases for memory protection Igor Stoppa
2018-10-24 3:27 ` Randy Dunlap
2018-10-24 14:24 ` Igor Stoppa
2018-10-25 16:43 ` Dave Hansen
2018-10-29 18:16 ` Igor Stoppa
2018-10-23 21:34 ` [PATCH 07/17] prmem: lkdtm tests " Igor Stoppa
2018-10-23 21:34 ` [PATCH 08/17] prmem: struct page: track vmap_area Igor Stoppa
2018-10-24 3:12 ` Matthew Wilcox
2018-10-24 23:01 ` Igor Stoppa
2018-10-25 2:13 ` Matthew Wilcox
2018-10-29 18:21 ` Igor Stoppa
2018-10-23 21:34 ` Igor Stoppa [this message]
2018-10-29 11:45 ` [PATCH 09/17] prmem: hardened usercopy Chris von Recklinghausen
2018-10-29 18:24 ` Igor Stoppa
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